Imaging devices often use amorphous semiconductor or semiconductor layers (made of materials such as amorphous silicon, organic semiconductors or amorphous selenium) integrated with pixelated electronic readout arrays to image objects using radiation such as X-ray, gamma rays, high-energy electrons, and beta particles. However, amorphous semiconductors are especially well known to suffer from memory effects including image lag (which manifests itself as persistence of the acquired image after acquisition is completed) due to charge trapping within the semiconductor bulk as well as at the interfaces between layers. The subsequent erratic release of this trapped charge further increases the image lag.
This lag typically translates into slower speed readouts that limit or reduce large area detector operation speed. This is problematic as mammography tomosynthesis X-ray detectors usually need to acquire data at greater than a single frame per second. Moreover, charge trapped near a particular sensing pixel can result in the image being recognized on adjacent pixels across multiple frames resulting in a degradation of spatial resolution.
Spatial resolution is often measured using the modulation transfer function (MTF) metric and MTF degradation serves to fundamentally limit high-resolution X-ray detectors that are preferred for their ability to resolve small feature sizes. This charge trapping can affect many different imaging applications.
Emerging applications such as mammography tomosynthesis or mammography-computed tomography (CT) typically require high-resolution (i.e. high MTF) X-ray detectors with minimal lag.
Thus, there is provided a novel method and apparatus for a high resolution, high speed radiation imaging.